Goldfish Eating Lake Ellyn Dwellers Out Of House And Home

Cory Atwell remembers the day someone reported seeing a sunken orange Volkswagen in Lake Ellyn in Glen Ellyn. It turned out to be a false alarm, but the true explanation was even more troublesome.

Goldfish.

The orange mass that one passerby mistook for a car two years ago was a school of rogue goldfish. Since then, the school has spawned and grown to monstrous proportions.

It may have begun with just one family's discarded pets. But now more than 350,000 of the slippery creatures populate the 11-acre lake, according to Atwell, Glen Ellyn Park Districts' superintendent. Some are a foot long.

With no natural predators to cull the population, Atwell said, there appear to be only two ways to bring the hoard under control: Drain the lake and start fresh, or poison it.

The problem at Lake Ellyn is emblematic of a growing crisis for America's freshwater fish, as more and more non-native species are introduced in local lakes and ponds, often with disastrous results.

"That may be the biggest threat to native fishes across the country," said David Philipp, director of the Center for Aquatic Ecology at the Illinois Natural History Survey in Champaign.

Individuals who think they are doing a fish a favor by releasing it into a lake or stream often end up doing widespread harm, Philipp said.

That is what appears to have happened to Lake Ellyn.

"Somebody put in Adam and Eve of the goldfish," Altwell said. The massive population in the lake probably "grew from two goldfish."

"People dump in their goldfish thinking, `Well, we're just turning them loose in the lake, and that'll be nice for them.' Then they spawn," Atwell said. "A little goldfish turns into 8 inches pretty quick, living in a lake."

Lake Ellyn happened to be the perfect place for goldfish to establish a foothold and thrive.

In most waterways, predator fish quickly nibble up any hapless goldfish that has the misfortune to be liberated. For example, in the 14 lagoons of Chicago, there are no current reports of goldfish infestations, according to Park District spokeswoman Cheryl Hislop.

In Lake Ellyn, officials five years ago undertook a massive renovation project that involved draining the lake and making it deeper. After the lake was refilled with water, a variety of fish species were reintroduced.

Atwell figures that is when someone added the goldfish to the mix.

"The predators that were introduced four years ago were too small, and the goldfish outgrew them too quickly," Atwell said.

By the time the predator fish had grown large enough to eat the goldfish, there apparently were enough goldfish to disrupt the egg nests of other fish and to hold their own.

Goldfish, which are related to carp, consume plant matter by sucking at the bottom of a lake, stirring up muck and disturbing fish eggs. That means Lake Ellyn has become an inhospitable environment for other fish and for many species of plants and insect, Atwell said.

Last summer, conservation officials used an electrical shock to render fish temporarily unconscious in the lake. That allowed for an accurate count of the goldfish, which far outnumber the meager population of bluegill, bullhead and bass, Atwell said.

Goldfish are not the worst of the non-native fish that threaten freshwater habitats.

"In Illinois, for example, the round goby has been touted as a great, natural bait for small-mouth bass," Philipp said. As a result, he said, some anglers are taking the fish from Lake Michigan and introducing them to other inland waterways in their attempts to use them as bait.

The round goby, native to waterways on the other side of the Atlantic Ocean, is a non-native fish that has begun to thrive in Lake Michigan. The fish eats the non-native zebra mussels that also were brought here in bilge water from abroad. Together, the aquatic transplants are helping transform the ecology of the Great Lakes.

Fishing enthusiasts are spreading the scourge inland, Philipp said.

Increasingly, minnows bred in one state are shipped across the country for use as bait, Philipp said. Some inevitably are released into lakes and streams where they do not normally live. It is becoming more common for such transplants to wreak havoc with local ecologies, eating indigenous fish eggs or otherwise upsetting the food chain, he said.

The Glen Ellyn Park District board is considering a new renovation of the lake, Atwell said. The project would include more than just eradicating the goldfish. Board members also hope to establish public access points to the lake, enhance the water quality, bring in desirable fish species, and create a more scenic shoreline.

The total cost would be $200,000 to $300,000, Atwell said, of which about $20,000 would go toward eliminating the goldfish.

The board hopes to award a contract in December or January so that work can be done in the spring and summer, he said.

Meanwhile, the goldfish have the run of the place.

"When you throw food into them, it looks like piranha, they go so fast," Atwell said, though noting that the goldfish are actually not dangerous to people. "It's incredible."